The present invention relates to a roof or wall covering made of sheet material and comprising alternate wider and narrower strips, the outwardly oriented surfaces of which are concave and convex, respectively, and which have interengaging, folded longitudinal edge zones, and fastening members for securing the covering to a supporting substructure.
From Danish Patent Specification No. 134 789 there is known a roof covering of this kind in which the cross sectional profile of the edge zones of the concave strips is U-shaped while the profile of the convex strips is C-shaped. For assembling the covering each convex strip is slid longitudinally into engagement with two adjoining concave strips, with each of its edge zones located between the limbs of the U-shaped edge zone of a concave strip. The convex strips serve for creating a watertight connection between the concave strips which, according to the patent specification, are secured to a supporting substructure in a conventional manner not described in any detail.